I've heard that heavy arrows with more momentum (like from a war bow) were more effective against armor than lighter faster arrows.
This video shows some penetration testing with different weights of arrows.
http://www.youtube.com/watch?v=VAfK0sBsZBw
All the arrows used are light in comparison to English war bow arrows, but you can see the lighter arrow penetrated more than the heavier arrows.
I've also seen other tests where heavier arrows penetrated more than lighter ones.
Does anyone have any ideas on how this would translate to arrows against armor?

Light arrows tend to fly faster and have a flatter trajectory. Heavy arrows are better for punching through armour. I think it was King Charles who bemoaned the fact that nobody could shoot a quarter-pound arrow anymore.

A heavier arrow from the same bow always[1] has more energy and more momentum. Somewhat more energy, and a lot more momentum. The lighter arrow always has more speed. To check this, one ideally uses a chronograph, rather than indirect tests like penetration. Some tests showing variation in speed with arrow weight: http://www.atarn.org/islamic/akarpowicz/turkish_bow_tests.htm ; note that the "efficiency" is the fraction of stored energy transferred to the arrow. From a given bow, the efficiency tells you the kinetic energy (or you can calculate it from the weights and speeds).

For penetration into soft tissue, penetration is limited by viscous drag (mostly). In this case, more momentum gives more penetration.

Where penetration is limited by friction (like a lot of archery targets), then more kinetic energy gives more penetration. Assuming that the frictional force is the same for different arrow speeds. Which it won't necessarily be, since the target deforms. Perhaps this is responsible for some of the test results?

For penetration through armour (metal or rawhide hard armour, at least; not sure about textile and fibre armours), more energy gives more chance of penetration. To put an arrowhead through a steel plate, you need to cut through the steel, and curl the edges of the cut out of the way. This takes a certain amount of energy. Only by exceeding that energy can you go through. This is supported by plenty of testing; a summary is given by Atkins in The Science and Engineering of Cutting.

Manually shooting arrows from a bow is a poor way to test - too many ways to vary the draw and get the result you want, even if unconsciously. Karpowicz's shooting machine in the tests linked above is much better. Other good test methods include pneumatic launchers or drop-weights (which eliminate (or at least greatly reduce) effects of arrow spine). A manual-shooting test would ideally have the arrows shot through a chronograph.

[1] Where "always" means that the draw and release are identical, and we're ignoring energy that goes into flexing the arrow."In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.

I'll just add an explanation of how an arrow like a quarter Pound or even heavier could be made.

The weight of the Arrow depends on a number of facotrs:

-The arrowhead shape, overall size and of course material used will affect weight. We'd expect iron or better yet tempered steel if one is to peirce metal based armour though. But there were Arrows made with hardwood tips in medieval times. Some are enbedded in an old fortified log house from 14th Century at the Skansen heritage outdoors museum here in Stockholm, Sweden, showing plenty of penetration even with such crude arrowheads.

- The type of wood used, oak would be far heavier than say the same size ash but also more liable to crack rather than bend.

- The shape of the Arrow shaft for example conical with a wider back end than at the point which also helps vs splitting while being shot with a really Heavy bow. Lighter flight arrows could be made straight or close to it just like modern target arrows.

One must also remember the length of the Arrow used, most modern made Arrows are considerably shorter than say for an historical warbow which is drawn further. One way to make and Arrow heavier would be to simply make it longer, though at some point it would become unweildy and impossible to shoot."The Dwarf sees farther than the Giant when he has the giant's shoulder to mount on" -Coleridge

1: bows don't scale linearly with draw weight, diminishing returns set in quickly
2: heavier arrows are required to get benefit from a heavy bow, so if you are shooting a 120lb war bow a light arrow is not an option the arrow would most likely shatter or even shoot slower then in a lighter bow
3: even a relatively inefficient bow like an English Longbow packs more then enough energy to kill anything without armor at pretty low draw weights (say 70lbs or thereabouts) so the only reason I can think of for massive bows in punching through some degree of armor
4: the only way to really tell what would happen when you shoot armor is to shoot armor. Similarly the best way to tell what happens when you shoot flesh is to shoot dead animals , which is what a lot of the modern day testers do
5: even modern recurve and reflex/deflex "longbows" are significantly more powerful then ancient bows. This is true even for bows that are made mostly of traditional material, the only real equivalent to an English Longbow is something very close to the original design

3: even a relatively inefficient bow like an English Longbow packs more then enough energy to kill anything without armor at pretty low draw weights (say 70lbs or thereabouts) so the only reason I can think of for massive bows in punching through some degree of armor

IMO the whole point of English warbow tactics was to cast a heavy war arrow out to a range that was long enough to provide tactical options to a commander. In France their main goal was to redress the English deficiency in cavalry. You need to be able to start shooting early enough to disrupt a cavalry charge before it gets to your front rank - 250 yards is a good ball park. You need mass volleys of arrows that are heavy enough to upset a horse at these ranges, which means heavier bows, which means finding lots of soldiers with the training to use these bows. Punching through armour only comes into play when the archer is very close (and even then only lighter armour is vulnerable) so this tactic is only useful in very limited situations. I also think that the bodkin arrowhead was intended for English long-range arrows and the steeled compact broadhead was the armour-piercer used at shorter ranges.

I've said this before but the only test where an attempt was made to use accurate replicas of both bows AND armour was the Defense Academy warbow trials at the Royal Armouries. It wasn't perfect but it was far better than any other test I've seen.
http://www.swordforum.com/forums/showthread.p...blication.

There might be a relationship between accuracy at that range and the weight of the arrow, or a relationship between armor piercing ability. Could also be there is some peculiarity of English longbows that drive toward heavier bows giving longer shots

Please read the Ashby report for details on arrow effectiveness on animals;
http://www.alaskabowhunting.com/Dr.-Ed-Ashby-W26.aspx
Heavier is better in pentrating flesh and bone with arrow heads strikingly similar to those used throughout pre-history. 50lbs draw weight is reckoned to be enough to kill any animal in North America including Elk (alces alces) and Bear (ursus arctos). I would have thought the idea behind the heavy draw weights (estimates aren't they?) of some historical bows was to maintain effectiveness at long ranges. Effective and lethal not being the same thing.

I would have thought the idea behind the heavy draw weights (estimates aren't they?) of some historical bows was to maintain effectiveness at long ranges. Effective and lethal not being the same thing.

It doesn't appear that heavy (say, 80g, or 1000gr, or wherever we want to draw the line, and up) arrows are needed to be effective at long range, against horses and unarmoured soldiers. Ming and earlier Chinese, Korean, Indian, Turkish, and Mongol use of arrows in the 20-40g range, out to long range, effectively, shows this.

In East Asia, we have Manchu/Qing bows, and Japanese bows sacrificing range and accuracy for energy, and accepting very short archery battle ranges. Very heavy arrows, often 100g and more. To do so in an attempt to defeat armour makes sense. It certainly wasn't for long range performance."In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.

The hunting information is interesting, but I don't know how applicable it would be. There's a big difference between shooting from an ambush at point targets 30 yards away or less and shooting at 300 yards at massed troops/cavalry who are wearing armor and wounding them is just as good as killing.

Certainly, for plunging fire, a heavier arrow is going to retain much more energy and have a higher terminal velocity than a lighter arrow. Trajectories are never parabolic because the arrow slows down as it travels. At extreme range the arrow will be falling close to vertical.

I don't know that many arrows would even be used at direct fire ranges (<70 yards) - at least under the English system. As mentioned, the ability to disrupt cavalry at long ranges was the killer app.

Here is Hardy's summary of his tests from The Great Warbow (p. 18): Warbows of 143-165 lbs shooting arrows weighing 3.5-4.0 oz. flying as far as 240 yards and losing 15-30% of their initial velocity at the point of impact. Lighter arrows lose a lot more of their initial velocity than this.

Here is Hardy's summary of his tests from The Great Warbow (p. 18): Warbows of 143-165 lbs shooting arrows weighing 3.5-4.0 oz. flying as far as 240 yards and losing 15-30% of their initial velocity at the point of impact. Lighter arrows lose a lot more of their initial velocity than this.

Which means losing 30-50% of their initial energy. Which means they are likely to be ineffective against even thin plate (e.g., limb armour, which close range shooting should be able to penetrate, given a non-glancing hit).

It also leaves them with far more energy than is needed to be effective against unarmoured targets.

Given that increasing the draw weights of bows reduces the pool of capable archers, and reduces the effectiveness of archers in the field due to fatigue, lack of food, disease, etc., there should be some benefit. Long-range shooting against light armour - maybe textile armour? - or short range anti-armour are candidates IMO. Is the former likely to be useful enough?"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.

Especially after their conquest of China (but it began beforehand, when they started to include significant Chinese forces in their army decades before the conquest), their archers were cavalry. Early Qing armies can be described as mounted archers, pike and musket infantry, and artillery, and leftover Ming forces (which would often fall into the previous categories, anyway). Long range anti-armour came from jingals, long-range extra-heavy muskets (or ultra-light artillery, if you prefer), two-man crew and fired from a mount.

Japanese archery was, as far as I can tell, similar, even before muskets became dominant on their battlefields. Manchu archery was high-energy short-range before they went firearm heavy as well, AFAICT also. So, I wouldn't say that the Manchu focus on high-energy short-range shooting resulted from guns."In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.

Long-range shooting against light armour - maybe textile armour? - or short range anti-armour are candidates IMO. Is the former likely to be useful enough?

There is really no such thing as "light armour" on the battlefield. Textile armour is just as effective as light plate - it is just thicker and weighs more. If the armour didn't protect adequately then you either add more layers till it did, or you discard it completely. A heavy warbow isn't going to get through any kind of armour unless it is at close range.

Long-range shooting against light armour - maybe textile armour? - or short range anti-armour are candidates IMO. Is the former likely to be useful enough?

There is really no such thing as "light armour" on the battlefield. Textile armour is just as effective as light plate - it is just thicker and weighs more. If the armour didn't protect adequately then you either add more layers till it did, or you discard it completely. A heavy warbow isn't going to get through any kind of armour unless it is at close range.

Why no light armour? We see light armour on the battlefield now, and have for a century at least. Armour that stops shell splinters, but not bullets. Armour that can stop 9mm SMG bullets, but not rifle bullets, armour that can stop small arms fire, but not heavy weapons. The key word is "adequate". Adequate is a compromise, and where you choose to compromise can result in rather light armour today. Why should this not be the case in the past?

The question would be whether armour that a warbow can get through at long range would provide adequate protection against a common threat. If so, why would it not be used? If not too heavy, too expensive, or whatever, and still useful, why not use it.

For example, the buff coat. If it was effective against all threats, why would anybody ever wear a breastplate over it? But if it was useless on its own, why anybody ever wear it without a breastplate. Yet it was done.

But that's a little beside the point. The point is whether or not such targets were common enough for it to be worthwhile going to very high draw weights in order to obtain energies in excess of what is needed against unarmoured targets at long range. If no, then very high draw weights are not about range. If, say 80lb draw weights deliver enough energy against unarmoured targets at long range, and 140lb doesn't provide enough against armour at long range, then 140lbs isn't used for long range performance.

Unless, perhaps it gives a little edge against opposing archers. Perhaps European accounts of archers vs archers might illuminate?"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.

For example, the buff coat. If it was effective against all threats, why would anybody ever wear a breastplate over it? But if it was useless on its own, why anybody ever wear it without a breastplate. Yet it was done.

As far as I can tell, buff coats were mainly worn because they were not susceptible to powder burns. They could stop a sword cut, but so can any winter coat.

I have limited knowledge and experience with archery but wouldn't it be reasonable to assume that factors affecting the armour penetration of arrows would be similar to those of other projectiles? If so, my assumption would be that the most important attributes affecting armour penetration would be the shape of the arrowhead, density of the material used in the arrowhead versus that of the armour, and speed. I don't think weight would necessarily be as important other than its effect on the speed of the arrowhead and as a result of its density. The efficiency of the arrowhead in preserving its energy as it strikes the target would probably be what determines its effectiveness so a heavy arrowhead that decelerates too quickly wouldn't work well.

Looking at modern day projectiles, a 45 caliber pistol round is heavy compared to other pistol rounds but has relatively poor performance due to its lower velocity and shape. An armour piercing 9mm round is smaller and lighter but has higher velocity and is made out of denser materials which makes it better at punching through armour but may possibly compromise its effectiveness against "soft" targets.

Long-range shooting against light armour - maybe textile armour? - or short range anti-armour are candidates IMO. Is the former likely to be useful enough?

There is really no such thing as "light armour" on the battlefield. Textile armour is just as effective as light plate - it is just thicker and weighs more. If the armour didn't protect adequately then you either add more layers till it did, or you discard it completely. A heavy warbow isn't going to get through any kind of armour unless it is at close range.

Military study has shown that about 50-70 lbs is what a man can carry and still fight effectively. A soldier wearing textile or a soldier wearing plate will both be "heavy" up to that weight limit, but the man in plate will be better protected. 50 lbs of plate protects better than 50 lbs of mail which protects better than 50 lbs of jack.

I do agree that long range missile fire pretty much has to be resistable by contemporary armor - otherwise the whole body of medieval tactics goes out the window. It happened with guns not longbows. Probably what you were getting at anyway.

Probably the point of having a heavy arrow at long range is as an anti-horse weapon. They're the lightly protected soldiers on the field.

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